Scum-removing device



Feb. 5, 1929. 1,700,791

H. E. ELROD SCUM REMOVING DEVICE Filed April 16. 1927 '7 Sheets-Sheet 1 gn n ifs-I s "1% 1 lg w -i l u l- INVENTOR u l Velzzyrad MIM Wh f5 Feb.5,1929.l 1,700,791

H. E. ELROD sCUM REMOVING DEVICE Filled A ril 16, 1927 y 7 Sheets-Sheet 2 i l I R i I P u 'A m im BY v ATTORNEYJ Feb. 5, 1929.- i 1,700,791

H. E. ELROD SCUM REMOVING DEVICE Filed April 1e, 1927 7 sheets-sheet 3 INVENTOR. V

- Feb. 5, i929.

H. E. ELROD scUM REMOVING DEVICE Fiied April 1e, 1927 '7` Sheets-Sheet 4 A TTORNEY/j' Feb. 5, 1929.

H. E. ELROD SCUM REMOVING DEVICE Fi'ied April 16, 1927 '7 Sheets-Sheet 5 Y INII/ENTOR. myrod A TTORNEY Nh Nk Smm Feb. 5, 1929. 1,700,791

H. E. ELROD SCUM REMOVING DEVICE Uhn By,/W

ATTORNEYS Feb. 5, l'119229.

H. E. ELROD SGUM REMOVING DEVICE Filed April 16, 1927 7 Sheets-Sheet 7 J ,.rl

I N V EN TOR; /Ysmy md A TTORNEYJ` Pafenfea Feb. 5, 1929.

UNITED. STATES HENRY E. ELROD, OF SANTA MONICA, CALIFORNIE.

soUM-nEMovING DEVICE.

Application led April 16, 1927.- Serial No. 184,350.`

This invention relates to a device for removing scum from the surface of a tank of liquid. The invention consists of a skimmer mounted on a carriage which is adapted to be 5 periodically moved across the surface of the liquid, the skimmer having a fin or scraper which extends a shortl distance below the surface of the `liquid and drives before it the scum which has risen to the surface during l the preceding period of rest of the carriage.

In the following specification certain embodiments of the invention will be described by way of example as applied to a pre-set tling tank for sewage purifying systems,

lI 'though it will be obvibus that the invention may be applied to various other systems' where the periodic removal of scum from a tank of liquid is desirable.

Scum arising on the pre-settling basinsof sewage treatment works is one of the great nuisances encountered in the treatment of sewage. and heretofore, 'has had to be removed by hand, or hosing,' at a great expense of time and discomfort to nose and eye.

My invention is designed to eliminate the inconvenience of the old method, being an eilicient mechanical device, preferably automatic in its operation, but in its simplest form being adapted to be operated by hand.

In the drawing Fig. 1 is a cross section of a tank showing one form of skimming device according toy my invention in front elevation,

Fig. 2 is a side elevation of the tankland skimming device, parts of the tank being shown in section,

Fig. 3 is a section on the line 3- 3 of Fig. Fig. 4 is a longitudinal section of a portion gf the skimming device showing the switch Fig. 5 is a section on the line 5-5 of Fig. 4, Fig. 6 is a section on the line 6-6 of Fig. 4, Fig. 7 is a section on the line 7 7 of Fig. 4, Fig. 8 is a section on the line 8-8 of Fig. 7, Fig. 9 is a wiring diagram, Fig. 10 is a detail view of one of the motor or gear speed reducer supports, Fig. 11 is a vertical section through a portion of the tank,

Fig. 12 is a detail view of an air valvev used in connection with lthe device, and

Fig. 13 is a side elevation of a simplified form of the device with parts shown in section. Y

The embodiment shown in'Figs. 1 'to 12 will be first described.

The sides 1 of the pre-settling tank are provided along their inner edges with angle bars 2 secured to the sides by anchors 3 set into the concrete. The bars 2 serve as tracks for wheels 4 secured to shafts 5 which are4 journalled in bearings '6 of a frame 7 upon which the skimmer and the driving mechanism are mounted. The frame 7 consists of plates 8 to which the bearings 6 are secured, channel beams 9 supported on said plates, angle bars 10, angles 11, and battons 12, all secured together by rivets "or other suitable means to form a rigid structure.

A downwardly projecting plate 13 -is secured to the bottom of plates 8 andlower battens 12 by means of angle bars 14 the parts being riveted together, and a thin spring brass fin or scraper 15 is secured between a bar 16 and the lower edge of plate 13 by rivets. The iin 15 extends preferably about an inch below the surface of the liquid in the tank and reaches. from one side of the tank to the other.

A motor 17 and gear speed reducer 18 are mounted on angle bars .19 having extensions 20 riveted to the upper flanges of channels 9 as shown in Fig. 10. The motor and speed reducer are connected by a coupling 21. The

shaft 22 of speed reducer 18 is provided with a sprocket 23, and a chain 24 connects this sprocket to a sprocket 25 on a shaft 26. A; gear 27 on shaft '26 meshes with a gear 28 on a shaft. 29. The shaft 29 and shafts 5 have sprockets 30 and`31 respectively, and a single chain 32 runs overall three sprockets. Idler sprockets 33 guide the chain around the channels 9. Additional bearings 34 are provided for the shafts 5 adjacent sprockets 31. A trapezoidal bar 35 braces the channel beams at their midpoints where the driving gear is located.

Across each end of the tank extends a scum trough 36 formed ,by a concrete ledge 37. The upper inclined surface 37 of the ledge is protected by an angle bar 38 anchored to the ledge by bolts 39.

Assuming the carriage to be at one end of the tank, if the motor is started the rotation of the motor will be transmitted through the above described gear to the shafts', causing them to rotate the wheels 4 and thusmove the carriage along the tank, the fin 15 pushing before it the scum lying on the surface of the liquid. When the carriage reaches the other end of the tank the fin scrapes over the plate 38, pushing the scum into the scum trough 36. The carriage is stopped at eachend of its travel by an automatic time switch, which will be presently described, and which after a predetermined period of rest reverses the motor and starts the carriage back toward the other end of the tank. y

At each end of the tank is arranged a pipe V40 having a lower extension 41 passing through the wall 1 into the tank below the surface of the liquid as shown in Fig. 11, and an upper extension 4 2 passing through the wall 1 just above the trough 36. An air pipe 43 extends down through the center of each pipe 40 to a point near the bottom thereof. Each pipe 43 is connected to a source of compressed air which is controlled by a quick opening valve 44. Each valve 44 has a handle consisting of two sections 45 and 46 pivoted tgether by. a spring hinge 47. A spring 48 normally holds the handle in upright posi- 'tion so that section 46 will b e engaged by the nearest shaft 5 of the carriage, just before the .latter reaches the end of its travel, and will be thereby turned to open the valve. l When the carriage reachesthe limit of its travel the valve handle is released and springs back to upright position under the action of a spring 48. On the return movement of the carriage section 46 of the valve handle turns on spring hinge 47 as the shaft 5 passes and then snaps back into upright position. The valve may be constructed in the manner shown in detail in Fig. 12, the particular form of the valve being immaterial so far as the present invention is concerned. Between the valve inlet 120 and the valve outlet 121 is 'a diaphragm 122 having an aperture 123 controlled by avalve spindle 124. The end of the valve Spindle is pivoted to a yoke 125, the lower end of which is pivoted between two arms of a rigid fork 126. To the upper end of the yoke 125 is pivoted a cup 127 which receives the lower end of a spring 128 the upper end of which is held in a cup 129 pivoted on the lower end of section 45 of the valve handle. Section 45 is pivoted at 130 between extensions 131 of the fork 126. The valve handle is normally held in the position shown :in Fig. 12 by spring 48, the lower end of section 45 abutting against stop 132. The shaft 5-engages the upper end of section 46 of the handle and moves the same down, and then rides along the surface 133 holding the handle down. When the cup 129 ismoved to the right of cup 127 the spring 128 forces the yoke 125 out and opens the yalve.

. length of surface 133 -is such that the valve is held open a suiicient length of time to properly flush the scum trough. E When t-he handle is released by the shaft 5 spring 48 draws the same back against stop 132. The cup 129 is thereby moved to the left of cupv -127, and spring 128 forces yoke 125 in to close The f is opened some of the liquid in the tank is lifted up through pipe 40 by the air rising in lthe pipe, and discharged through opening 42 into the scum trough. The scum is flushed out of the trough, and may be conducted to the sludge digestion chambers of the plant.

The automatic reversing switch will now be described, with particular reference to Figs. 4 to 9'. A pair of bearings 50 are mounted on angle bars 51 bridging the channels 9, and secured thereto by the rivets 52. A metal Shaft 53,- preferably brass, is journalled in bearings 50. The shaft is provided with insulating bushings 54 and a metal sleeeve 55, preferably brass. A pair of nip-v ples 56 are screwed into threaded sockets 57 in the shaft'. The nipples support mercury chambers consisting of reducers 58,pipes 59, v

of sh oil, glycerine, or similar substancel 'which forms a thin layer 119 over the mercury and prevents sparking when the mercury leaves the contact.

- A rocking arm 65 is screwed into a socket 66 in shaft 5 3.' The lower end of the rocking arm is connected to a rigid arm 67 of a sliding yoke 68 by means of a link 69 of libre, `wood,

or similar insulating material. The yoke 68 has apertures 70 by which it is supported for sliding movement on a bolt 71 extendingV from one of the channels 9 to the other. The downwardly extending ends 72 of the yoke are tied together by a bolt 73 and are spacedby a `pipe 74. The bolt 73 and pipe 74 extend through a hole 75 in the plate 13.

The ends 72 of the yoke 68 extend down far `enough to engage the edges 76 (Fig. 2) of the end walls of the tank just before the Wheels 4 strike stops 77, whereby the yoke is shifted on bolt 71 and, through connections 69 and 65, rocks the mercury switch.

Between the channels 9 and adjacent the mercury switch is a box consisting of end plates 78 and 79, bottom plate 80, and cover 8l hinged at 82 to one of the channels. l The end and bottom plates are secured together and to the channels 9 by angle bars 83. The

channels themselves form the sides of the box. 'I

Upon the opposite sides of the box are mountverse the connections between the line wires and the motor. Each switch consists of an electromagnet 84, a set of stationary contacts 85, a set of movable contacts 86, and an armature 87 cooperating with the electromagnet. The armature 87 is mounted between two arms 88 fixed to the square shaft 89, andthe movable contacts 86 are fixed to the same shaft. so that the contacts 86 will be moved into and outof engagement with the contacts as the armature is attracted and released by the magnet. A hook 90 limits the outward movement of the armature.

Two vertical pipes 92 and 93 have their lower ends set in the end walls 94 and 95 of the' tank respectively and a guide wire 96 is stretched between the upper ends of said pipes. An electric cable 97 is led into the pipe 92 through the lower end 98 thereof, and passes upA through the pipe and out through a condulet 99 mounted on the upper end of the pipe. The electric cable, which is long enough to reach the full length of the tank, is fastened to insulators 101 and 102, and is supported intermediate the insulators by rings 103 sliding on guide wire 96 and tied to the cable at convenient intervals by rawhide thongs 104. The insulator 102 is mounted on an inverted V shaped frame 105 whose feet 106 are riveted to the channels 9, and whose upper end has an apertured extension 107 through which :the guide wire 96 is threaded. The end of the cable 97 passes through the line conduit 108 into the boX containing the magnetic switches, where it is connected to the stationary points of the switches (Fig. 9). An electric cable 109 leading from the movable contactsv86 passes through terminal conduit 110 to the terminals of the motor 17. A hole 111 having a bushing 112 is pro vided for the wires 114R, and 114L leading from the electrodes 64B, 64L, of the mercury switch into the switch box, where they are connected to the electromagnets in the manner shown in Fig. 9.

The operation is as follows: Assume the carriage to be approaching the left end of the tank as shown in Fig. 2, in which case the various part-s willbe in the positions indicated in Figs. 5 to 9. At this time current is flowing from line wire 973 through wire 97R3, wire 117B, magnet coil 84B, wire 114B, electrode 64K, mercury 113, shaft 53, binding post 116, wire 115, to line wire 97,. The magnet 84R is therefore energized and contacts 86B are held in engagement with contacts 85R,therebycon neet-ing the line wires to the terminals of the motor inthe proper order to cause the motor to move the carriage to the left. The circuit of magnet coil 84L is open and contacts 86L are therefore out of engagement with contacts 85L. VA t about the time the scum begins to pass overI the plate 38 under the influence of the fin 15 the shaft 5 strikes the handle` 46 of the valve 44 and turns the same so that spring 128 passes over dead center and throws the valve open. The air flowing from pipe 43 rises in pipe 40 lifting with it liquid from the tank, which is discharged through opening 42 into the scum trough 36, thereby flushing the scum out of the trough. The flushing of the trough continues until the carriage just reaches the end of its travel, when the handle 46 is released by shaft 5 and snaps back under the action of spring 48, thereby closing the valve 44.

Meanwhile, just before the carriage reaches the end of its travel, the extension 72 of yoke 68 strikes the edge 76 of the end wall of the tank, and as the carriage continues to move to the left the yoke 68 is shifted along bolt 71 and rocksl the mercury switch so that its.

right end moves up and its left end down. The mercury leaves the electrode 64E thereby cutting oft thefcurrent to magnet- 84R so that armature 87H is released and contacts 86B move out of engagement with contacts 85B,

.thereby cutting olf the current to the motor.

The carriage continues to coast for a short distance under its own momentum until the wheel 4 strikes stop 77, at which time the left end of the mercury switch is in its-lowermost position. The mercury begins to flow through apertures 61 and 63, the speed of liow being determined by the adjustment of the screw 62. lVhen the `mercury has risen in the left hand mercury chamber to such a height that it touches electrode 64L current flows from line wire 97 3 through wire 97L3, 117L, magnet coil 87L, wire 114L, electrode 64L, 'mercury 113, shaft 53, binding post 116, wire to line wirez971. The magnet 84L is thereby energized and draws contacts 86L into engagement with contacts 85L, whereby' the line wires are connected tothe terminals of the motor in reverse order and the motor is caused torotatein a direction opposite to its previous direction of rotation. The carriage therefore returns along the tank and lthe above described operations are repeated at the other end'.

A simplified arrangement is shown in Fig. 13. In this vcase the source of motive power is notV mounted upon the carriage itself but consists of a cable .140 running'on sheaves 141 and 142 mounted on uprights 143 and` 144 respectively. The ends of the cable 140 are fastenedV to the carriage 145 from which depends a plate 146 having on its lower edge 'a spring' brass fin orscraper 147. The sheave 141 may be rotated by suitable manually operable means such as the Vcrank 149, sprocket 148, chain 150, and sprocket 151, or by means of a motor of any kind connected by .a speed reducin gear to the sheave. The scum on the surfce of the liquid is scraped into scum trough 152 in the same manner as before.

Having described my invention, I claim:

1. In combination with' a tank containing liquid, a carriage mounted above the surface of the liquid, an electric motor, connections between said electric motor and said carriage for causing the carriage to move along the tank upon operation of the motor, a in depending from said carriage into the liquid in said tankand lying transversely to the tank, and a reversing switch for the motor operated by movement of said carriage toeither end of the tank.

2. In combination with a tank containing' liquid, a carriage mounted above the surface of the liquid, an electric motor, connections tank, and means Jfor shuttingfoi the current` to said motor when said carriage reaches either end of'said tank and starting said motor in reverse direction a predetermined lengthoi time after the current to it has been shut o i. l f v 3. In combination with a` tank containing liquid, a carriage mounted above the surface of the liquid, an electric motor, connections .between said electric motor and lsaid carriage .for causing the carriage to move along the tank upon operation of the motor, a fin de pending from said carriage into the liquid in said tank and lying transversely to the tank, and means for shutting 0E the current to said motor when said carriage reaches either end of said tank, and starting said motor in reverse direction a predetermined lenth of time after the current to it has been shut off, said last mentioned means comprising electromagnetic switches for reversing the .current to the motor, and a mercury switch -controlling said electromagnetic switches consisting of a shaft pivoted onsaid carriage, a pair ofchambers mounted on said shaft, an opening in said shaft connecting said chambers, an electrode in each chamber, said chambers being partially lled with mercury, andffmeans engageable with stationary bodies at the ends of the tank for rocking said'chambers alternately above and below a horizontal plane passed through the opening in said shaft. v

4. In combination with a tank containing liquid, troughs at the ends of said tank, the

upper edges of the inner sidesof said troughs lying substantially at the surface of the liquid, a pair of tracks running along thevsides of said tank, a carriage mounted above the surface ofthe liquid upon wheels adapted to runupon said tracks, and a fin of springy material depending from said carriage into the liquid and extending transverselyto said tracks, said carriage beingadapted to move from end to end'of said tank, the limit positions of said carriage being such that said .fin passes over the inner edges of said troughs.

5. In combination with a tank containing liquid, troughs at the-ends of said tank, the upper edges ofthe innersides of said troughs lying substantially at the surface of the liquid, a pair of tracks running along the sides of said tank, a carriage mounted above the 'surface of the liquid upon wheels adapted to run upon said tracks, a iin of springy material depending from said carriage into the liquid and extending transversely to said tracks, said carriage being adapted to move from end to end of said tank, the limit positions osaid carriage being such that said fin passes .over `the inner edges` of sai-d troughs, and means for ushing said troughs comprising pipes having inlet ends open to the liquid in said tankand outlet ends opening into said troughs, and means for moving a portion ofthe liquid'in said tank through said pipes into said troughs. i i

6. Incombinationwith a tank containing liquid, troughs at the ends of said tank, the

lying substantially at the surface' lo the liquid, a pair of tracks running along the sides of said tank, a carriage mounted above the.

.in passes over .thef inner edges of said troughs, and means oriiushing said troughs comprising pipes havinginlet endsopen to the liquid in said tank and loutlet ends opening into said troughs, means for introducing ,air into the lower ends of said pipes, and

valves controlling said air introducing means ladapted to be opened by said carriage near the ends of its travel.

The foregoing specification signed at Dallas, Texas, this 19th day of February, 1927..

.I HENRY E. ELRoD.

upper edges of the inner sides of said troughs l 

